Apparatus for drawing ellipses



g- 1961 B. w. HANCOX APPARATUS FOR DRAWING ELLIPSES Filed Aug. 6, 1957 IN V E N TOR. BUR rozv w. HA /vc0x W ATTYS.

United States Patent 2,996,804 APPARATUS FOR DRAWING ELLIPSES Burton W. Hancox, Eagle Road, Springfield, Pa. Filed Aug. 6, 1957, Ser. No. 676,562 2 Claims. (CI. 33-31 The present invention relates to new and useful improvements in ellipse drawing apparatus and more particularly to new and useful improvements in ellipse drawing apparatus which may be readily set to draw any desired size ellipse at any desired angle of projection.

The principal object of the present invention is to pro vide novel ellipse drawing apparatus which may be easily set to draw any desired size ellipse at any desired angle of projection. Prior apparatus of this type normally contained a single graduated scale and a pair of adjustable carriages which could be moved and set relative to the scale. In conjunction with this scale there was a relatively complicated set of charts or direction for computations which the user of the apparatus would have to follow to set the ellipse drawing apparatus for the desired size ellipse at the desired angle of project-ion. This was a primary disadvantage of prior apparatus of this type as it made the apparatus very difficult to use and prior to the present invention it was quicker to lay out an ellipse mechanically rather than use the ellipse drawing apparatus available on the market.

Another object of the present invention is to provide ndvel ellipse drawing apparatus which may be taken apart and stored in a relatively compact package and readily assembled for use. Prior apparatus of this type was relatively bulky and could not be easily stored, a disadvantage which prevented wide usage of this type of equipment.

A further object of the present invention is to provide a novel carriage construction for ellipse drawing apparatus which permits the tracer bar and scribe point to be easily moved to trace out or form the ellipse.

Another object of the present invention is to provide ellipse drawing apparatus of the above stated type having novel features of adjustment permitting the ellipse drawing apparatus to draw a series of concentric ellipses of different sizes with a single adjustment.

A still further object of the present invention is to provide novel ellipse drawing apparatus having the features and characteristics set forth, which is of relatively simplified construction, may be manufactured easily and cheaply, and is entirely eflicient and effective in operation and use.

These and other objects of the present invention and the various features and details of the operation and construction thereof, are hereinafter more fully set forth and described with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of the ellipse drawing apparatus of the present invention;

FIG. 2 is an enlarged fragmentary side elevational view partially in section of the ellipse drawing apparatus;

FIG. 3 is an enlarged transverse sectional view taken on line 3-3, FIG. 2 illustrating the construction of one tracer bar guide and the means for adjusting the position of the guide;

FIG. 4 is a perspective view of the tracer bar of the ellipse drawing apparatus of the present invention with one scale partially removed from the tracer bar;

FIG. 5 is a fragmentary side elevational view illustrating the means for removably connecting the two tracks;

FIG. 6 is a fragmentary plan view of the tracks of FIG. 5; and

FIG. 7 is an enlarged fragmentary front elevational view partially in section illustrating the adjustable front pivot pin which serves to position the tracks.

Referring more specifically to the drawing and particularly FIG. 1 thereof, the ellipse drawing apparatus of the present invention consists essentially of a tracer bar 10 mounted for movement above a pair of tracks 11 and 12 which extend perpendicularly to one another with the track 12 lying in the same plane as the track 11 and midpoint of the track 11. Movement of the tracer arm 10 is guided by means of front and rear carriages 13 and 14 which are adapted to travel along the tracks 11 and 12, respectively. The tracer bar 10 is adjustably interconnected with the front and rear carriages 13 and 14, as more fully described hereinafter, and has an enlarged portion 15 at the forward end thereof extending beyond the front surface of the front track 11 and provided with an opening through which a scribe collet 16 passes. The scribe collet 16 is held in position relative to the tracer bar by means of a knurled thumb screw 17 and has a scribe 18 secured thereto. The scribe 18 may be a metal stylus or a piece of drawing lead and is adapted to trace out the desired ellipse during operation of the ellipse drawing apparatus of the present invention.

With reference to FIGS. 1, 5 and 6, the tracks 11 and 12 each have guide means thereon operable to guide the movement of the carriages 13 and 14. The front track 11 comprises a base member 19 having a guide member 21 formed integrally therewith or otherwise rigidly secured thereto. A slot 22 having a restricted opening formed by a pair of inwardly extending wall portions is provided in the guide 21 and extends longitudinally of the track 11 for the entire length thereof. The rear track 12 is formed in a similar manner to the track 11 and consists of a base member 23 having a guide 24 thereon which may be formed integrally with the base member 23 or otherwise rigidly secured to the base member. A slot 25 having a restricted opening formed by a pair of inwardly extending wall portions on the guide 24 extends longitudinally of the track 12 for the full length of the guide 24. As set forth previously, the tracks 11 and 12 are removably secured together with the track 12 connected to the midpoint of the track '11 and extending perpendicularly thereto. The tracks 11 and 12 may be secured together as shown in FIGS. 5 and 6, by means of a pair of dowel pins 26, 26 projecting outwardly from the base member 23 of the track 12 parallel to the longitudinal axis of the track 12 and adapted to be received in a pair of openings '27, 27 formed in the base member of the track 11. By this construction the tracks may be readily assembled for use and disassembled for storage.

The carriages 13 and 14 are slidably mounted within the slots 22 and 25, respectively, of the tracks 11 and 12. With reference to FIGS. 1, 2 and 7, the carriage 13 has a pair of flanged wheels 2%, 28 rotatably mounted thereon, for example, by means of rivets 29 which extend upwardly through the Wheel 28 and are secured within the body portion of the carriage 13. The wheels 28, 23 extend downwardly through the slot opening into the slot 22 with the flange portions of the wheels beneath the inwardly extending walls defining the slot opening, as shown in FIG. 2, so that the carriage may not fall out of the slot 22. The rear carriage 14 is formed in a manner similar to the front carriage 13 and has a pair of wheels 31, 31 rotatably mounted thereon, for example, by means of a pair of rivets 32, 32 with the wheels 31 projecting downwardly beneath the carriage and received in the slot 25 of the short axis track 12. The flanges of these wheels 31 lie beneath the inwardly extending walls of the track 12 which define the opening to the slot 25 so that the carriage 14 will not fall out of the slot 25 during use of the ellipse drawing apparatus.

According to the present invention, the tracer bar overlies the tracks 11 and 12 and is interconnected with the carriages 13 and 14 so that its movement is guided by the tracks. To accomplish this a front tracer bar guide member 33 and a rear tracer bar guide member 34 are pivotally secured to the carriages 13 and 14, respectively, and are interconnected with the tracer bar 10. The front guide member 33, as shown in FIG. 2, is pivotally mounted on the upper surface of the front carriage 13, for example, by means of a rivet 35 which projects upwardly through the carriage 13 and is received in the front guide member 33. The carriage 13 is extended forwardly of the track 11 so that the axis of rotation of the guide member 33 relative to the carriage 13 is in alignment with the front edge of the track 11. A generally rectangular opening 36 is provided extending through the front guide member 33 within which the tracer bar is received and the tracer bar is fixed in position relative to the guide member 33 by means of a knurled locking screw 37 threaded through the guide member 33 into engagement with the upper surface of the tracer bar 10. The rear tracer bar guide member 34 is formed in a manner similar to the front guide member 33 and is pivotally mounted on a forwardly extending portion of the carriage 14, for example, by means of a rivet 38, as shown in FIGS. 2 and 3. A generally rectangular opening 39 is provided extending through the guide member 34 within which the tracer bar is received and a knurled locking screw 41 is threaded through the guide member 34 into engagement with the upper surface of the tracer bar 10.

During use of the ellipse drawing apparatus of the present invention, the tracks 11 and 12 are positioned on the surface of the article on which the ellipse is to be traced with the forward edge of the track 11 lying on the long axis of the ellipse and the tracks 11 and 12 are secured in this position on the surface of the article on which the ellipse is to be drawn by means of a pair of locating pins 42 and 43. The locating pin 42 is adjacent the forward surface of the track 11 and is adjustably secured thereto to permit accurate centering of the instrument. With reference to FIG. 7, the locating pin 42 is secured to an adjusting plate 44, for example, by welding or soldering and the pin plate is positioned in engagement with the forward surface of the track 11. A pin retaining plate 45 is then positioned in front of the adjusting plate 44 and secured to the forward track 11, for example, by means of a pair of bolts 46 extending through openings in the plate 45 and threaded into the track 11. By this construction the bolts 46, 46 may be loosened and the position of the pin 42 adjusted longitudinally of the track 11. The 10- cating pin 43 is carried by the track 12, as shown in FIG. 2 and is positioned relative to the track 12 by means of a sleeve 47 carrying the pin 43 which is secured within an opening in the base of the track 12.

After the tracks 11 and 12 are positioned on the surface of the article on which the ellipse is to be drawn with the forward edge of the track 11 lying along the long axis of the ellipse, the tracer bar is positioned relative to the guide members 33 and 34 with the scribe 18 in engagement with the surface on which the ellipse is to be drawn and the ellipse is drawn in the conventional manner by moving the tracer arm and carriage 13 from one end of the track 11 to the other end, thereby tracing out one-half of an ellipse E, as shown in FIG. 1. The other half of the ellipse is then drawn by rotating the ellipse drawing apparatus 180 and leaving the forward locating pin 42 in its original position. The distance between the scribe 18 and the axis of rotation of the guide member 33 relative to the carriage 13 will determine the length of the short axis of the ellipse, while the distance between the scribe 18 and the axis of rotation of the rear guide member 34 relative to the carriage 14 will determine the long axis of the ellipse, all in the conventional manner.

A primary feature of the present invention is the provision of means for permitting the ellipse to be readily set to draw any desired size ellipse at any desired angle of projection. To accomplish this, a pair of scales A and B are provided which may be read directly from the upper surface of the tracer bar 10. The first scale, scale A, is printed or etched or otherwise formed along the length of the tracer bar 10 on one-half of the upper surface thereof and is divided into uniform increments, for example, is graduated to indicate inches and is used to set the short axis of the ellipse being drawn. In order to set the short axis of the ellipse, the front tracer bar guide member 33 is positioned relative to the tracer bar 1%) with the beveled trailing edge of the guide member 33 immediately above the numeral on the scale A which indicates the desired diameter of the ellipse. The scale B may be printed or otherwise formed on an elongated narrow strip which is removable from the tracer bar and which may be inserted into a slot 48 projecting into the tracer bar from one side thereof and extending longitudinally of the tracer bar. A series of charts are provided for scale B with a separate chart for each desired angle of projection of the ellipse. The tracer bar may be made of a transparent material so that scale B may be viewed from the top of the bar as illustrated in FIG. 1. For example, when it is desired to draw an ellipse as viewed from an angle of 25 from the plane of the article being drawn, the 25 chart, shown in the drawings, is used for scale B. This chart is graduated relative to scale A so that there will be the proper ratio between the long axis of the ellipse and the short axis of the ellipse for an ellipse drawn at an angle of projection of 25". Similarly, each of the other charts for scale B (not shown) are also calibrated to provide the desired ratio between the long and short axes of the ellipse being drawn. The scale B is used to set the long axis of the ellipse and the rear tracer bar guide member 34 is positioned relative to the tracer bar 10 with the beveled rear edge thereof in alignment with the calibration on the scale B corresponding to the diameter of the ellipse being drawn.

The ellipse drawing apparatus of the present invention is illustrated in FIG. 1, set to draw an ellipse of an article 2" in diameter and viewed at an angle of 25 Thus, the guide member 33 is positioned at the 2 mark on scale A and the guide member 34 is positioned at the 2 mark on scale B, the scale B being the 25 scale in the present instance, and the ellipse drawn by this apparatus at these settings will be a true representation of a 2" circle viewed in perspective at an angle of 25. It can be readily seen that this ellipse drawing apparatus may be very quickly set without the use of any involved charts or directions or computations to draw any desired ellipse. An additional and relatively simple setting on the ellipse drawing apparatus of the present invention may be made when it is desired to draw an elliptical article in perspective. For example, if it is desired to draw an elliptical article having a 3" major axis and a 2 minor axis in perspective, as viewed from an angle of 25 the 25 chart is used for the scale B and the major axis is set by placing the rear tracer bar guide member 34 at the 3" mark on scale B. The minor axis is set by placing the front tracer bar guide 33 at the 2 mark on scale A, and the ellipse formed by the apparatus of the present invention is a true indication in perspective of the article being drawn.

Another important feature of the present invention is the provision of means for permitting the ellipse drawing apparatus of the present invention to be used for drawing a series of concentric ellipses, that is, a series of ellipses where each ellipse is spaced an equal distance from the next adjacent ellipse along its entire periphery.

This feature is particularly useful for commercial artists where, for example, they are providing a border or the like about a drawing with the border being formed of a series of concentric ellipses. This is accomplished by providing a spacer rod 49 fixed to the front tracer bar guide member 33, for example, by means of a retaining screw 51 and passing through an opening in the rear tracer bar guide member 34. An adjustable set screw 52 is threaded through the rear tracer bar guide member 34 and may be positioned in engagement with the spacer rod 49 to interlock the spacer rod with the rear guide 34. This fixes the distance between the guide members 34 and 33 at a constant distance and the initial ellipse is drawn, for example, with the above described settings. The locking screws 37 and 41, which interlock the front and rear guide members 33 and 34, respectively, with the tracer bar are then loosened and the tracer bar is moved relative to the guide members 33 and 34 a predetermined distance equal to the distance desired between the two peripheral lines of the two ellipses being drawn and the adjusting screws 37 and 41 are again tightened. The ellipse drawing apparatus is then used in the conventional manner to trace another ellipse which will be concentric with the first ellipse. When it is not desired to use the ellipse drawing apparatus to draw concentric ellipses, the adjusting screw 52 is loosened thereby permitting the guide members 33 and 34 to be moved relative to one another.

From the foregoing, it will be apparent that the present invention provides novel ellipse drawing apparatus which may be readily set to draw any desired size ellipse at any desired angle of projection. In addition, it will be apparent that the present invention provides novel ellipse drawing apparatus which may be easily set to draw a series of concentric ellipses and which may be readily taken apart for storage in a relatively small space.

While a particular embodiment of the present invention has been illustrated and described herein, it is not intended to limit the invention to such a disclosure and changes and modifications may be incorporated and embodied therein Within the scope of the following claims:

I claim:

1. Ellipse drawing apparatus comprising; a pair of elongated track members lying generally in a common plane and extending substantially at right angles to each other, a tracer bar overlying said track members, a carriage slidably mounted in each track for relatively free movement longitudinally of the tracks, means adjustably interconnecting said tracer bar with each of said carriages for longitudinal adjusting movement relative to each carriage separately, a first scale formed on said tracer bar graduated in predetermined units, an elongated narrow strip of material removably secured to said tracer bar adjacent said first scale, a second scale formed on said elongated strip of material, said second scale graduated in units equal to a predetermined ratio of the units of said first scale, means on one oLsaid carriages to indicate the reading of said first scale and the position of said one carriage relative to said first scale, and means on the other of said carriages to indicate the reading of said second scale and the position of said other carriage relative to said second scale so that the said carriages may be positioned relative to the said tracer bar to draw an ellipse with a predetermined ratio between the major and minor axes of said ellipse.

2. Ellipse drawing apparatus comprising; a pair of track members extending substantially at right angles to each other, a tracer bar overlying said track members, means interconnecting said tracer bar with each of said track members for movement relative to the track members, a first scale extending longitudinally of said tracer bar, means defining a longitudinal slot in said tracer bar extending inwardly of the tracer bar from one side edge thereof, and an elongated strip having a second scale thereon operable to fit within said longitudinal slot and extend longitudinally of the tracer bar.

References Cited in the file of this patent UNITED STATES PATENTS 436,166 Barrett Sept. 9, 1890 17,522 King Apr. 3, 1894 873,291 Beck Dec. 10, 1907 932,768 Dexter Aug. 31, 1909 1,031,780 Fine July 9, 1912 1,601,779 Thompson Oct. 5, 1926 2,326,412 Taylor Aug. 10, 1943 2,452,484 Noble Oct. 26, 1948 2,616,181 Van Dorne Nov. 4, -2

FOREIGN PATENTS 68,297 Germany May 5, 1893 80,177 Germany Mar. 7, 1895 587,241 Germany Nov. 1, 1933 561,817 Great Britain June 6, 1944- 

